Water is a huge issue in agriculture – just ask a Louisiana farmer watching floodwaters rise, or an Iowa farmer waiting to plant corn after a wet spring. But what if there was a way to better manage water with existing conservation practices?
That's the idea behind two ongoing research projects funded by the Leopold Center for Sustainable Agriculture at Iowa State University. The Center is betting that the answer may be related, at least in part, to riparian buffers.
The research is featured in three new videos, On the Ground with the Leopold Center. The short videos can be found on the Leopold Center web site at: www.leopold.iastate.edu/research/eco_files/ground.html, or on Iowa State's channels at iTunesU and YouTubeU.
Farming for untroubled waters, going beyond buffers
More than two million miles of riparian buffers have been planted along U.S. streams and waterways. Most areas are not more than 60 to 80 ft. wide, with diversified plantings of native trees, shrubs and grasses. Above ground, plant biomass slows the flow of water into streams and stabilizes stream banks; below ground, plant root systems use nutrients carried by runoff from crop fields and filter water before entering streams.
"We know that riparian buffers work very well to keep sediment and nutrients from runoff out of streams," says Leopold Center Ecology Initiative leader Jeri Neal. "But we tend to lose the advantage of their below-ground root systems by running tiles under them. We need conservation combinations, upslope farmland practices that can be used with buffers, to get us the best bang for the buck."
Dan Jaynes, a soil scientist at the USDA's National Laboratory for Agriculture and the Environment on the ISU campus at Ames, is studying what happens when tile drainage systems are connected to riparian buffers. A 1,000-ft. lateral line intercepts underground tile lines from a nearby crop field. The lateral line runs parallel to the stream, redistributing tile water throughout the buffer.
Manage water from tile drainage, and better use of riparian buffers
He hopes the system can divert 10% to 15% of the water from tile drainage, which would have gone directly into the stream. "That will take us a long way down the road to removing the critical peak of nitrate in water," he adds.
The second research project looks at groundwater quality and riparian buffers, specifically the impact of perennial vegetation in areas upslope from buffers. Principal investigators are Tom Isenhart, ISU Natural Resource Ecology and Management, and Keith Schilling from the Iowa Department of Natural Resources and Iowa Geological and Water Survey.
All research takes place at Bear Creek National Demonstration Watershed in Story County. This riparian buffer began 20 years ago, a small research project of the Leopold Center, but gained a national reputation. Today 10 landowners have built buffers along more than 10 miles of the creek. Isenhart was one of the original researchers at Bear Creek, along with colleague Dick Schultz.
Riparian buffer benefits, combined with other conservation practices
Schultz said he is interested in seeing how the buffer changes with time, possibly providing unforeseen benefits. For example, during the 2010 flood, Schultz says he noticed that almost all parts of the buffered stream bank covered by grass and/or trees had very little evidence of erosion. The buffer also caught flood debris, so the farmer didn't have to deal with it in the crop field.
"Usually we think of buffers as keeping things out of the stream, but during extreme flooding events they also have a reverse effect, keeping water in its place longer before it moves downstream," Isenhart notes. He says current research aims to discover additional benefits of riparian buffers, and how they can be combined with other conservation practices to become even more effective, especially in managing water.
"Once these things are established, it's the other benefits that farmers see and perceive and enjoy," adds Isenhart. "The wildlife, aesthetics and quality of life is what will keep people, but the incentives are what will entice them to keep the systems on the ground."